Generally speaking, there have been a number of significant improvements in the field of fuel injection in recent years. This is particularly true in the case of fuel injection systems for combustors of turbine engines wherein, for certain applications, it has been proposed to utilize tangential or semi-tangential injection by means of impingement surfaces located within tangentially directed air blast tubes. In this connection, this particular fuel injector utilizes what has become known as impingement fuel pressure atomization.
While considerably more efficient than swirl pressure atomization, there are nonetheless certain well recognized problems. These include the wide variety of operating conditions which can be encountered, i.e., low altitude operation which typically requires higher fuel flows and high altitude operation which requires very low fuel flows. Because of this inverse relationship between altitude and fuel flow, there has been a need to develop a fuel injection system that is highly versatile.
As mentioned hereinabove, one successful proposal has included utilizing tangential injection by means of impingement surfaces located within tangentially directed air blast tubes. This impingement fuel pressure atomization has represented a significant improvement for certain applications but, nonetheless, can suffer from certain deficiencies, particularly where it is desirable to mount the fuel injection system in the dome of the combustor. Because of the geometry of a turbine engine, it is essentially impossible to mount the fuel supply passage in an air blast tube in order to provide tangential or semi-tangential injection.
Because of this fact, fuel injection systems have typically been characterized by less efficient atomization in applications that require one or more dome-mounted injectors. This, in turn, is a problem in terms of efficiency as well as operation under the wide variety of operating conditions that can be encountered in practical applications. Furthermore, the absence of efficient atomization in combustors has resulted in undesirable amounts of smoke emissions therefrom.
In the case of smaller turbine engines, the exit diameter of the air blast tube is also proportionately reduced. Thus, on engines for smaller auxiliary power units, which can be, by way of example, on the order of as low as 50 horsepower, any significant blockage of the flow of compressed air through the air blast tube is not acceptable since the diameter of the tube carrying the fuel supply passage must remain relatively constant. While the number of injectors can be minimized to maximize the diameter of the air blast tubes, the problem nevertheless remains.
The present invention is directed to overcoming one or more of the foregoing problems and achieving one or more of the resulting objects.